<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript">
        var a="12";
        var b=12;
        alert(a==b);//true == 数值比较
        alert(a===b);//false ===全比较

    </script>
</head>
<body>

</body>
</html>